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Suma-cytotoxin ( Suma CTX), a three-finger toxin from Naja sumatrana venom, has previously been reported to induce caspase-dependent, mitochondrial-mediated apoptosis at low concentrations in MCF-7 cells, while progressing to membrane permeabilisation at higher concentrations. However, its effects on differential cellular proteomic alterations, particularly the relative abundance of apoptosis-associated protein remain inconclusive. Therefore, this study aimed to investigate the whole-cell proteome changes following Suma CTX exposure. MCF-7 cells were exposed to IC 20 , IC 50 , and IC 80 concentrations of Suma CTX for 8 and 24 h prior to label-free quantitative (LFQ) LC-MS/MS, and multiplex human apoptosis-associated proteins arrays. LFQ proteomics revealed distinct protein families that were differentially expressed at 8 and 24 h. At 8 h, differentially expressed proteins (DEPs) were associated with cell cycle regulation, ESR signalling, Notch, WNT/ β-catenin, and Rho GTPases pathways. In contrast, at 24 h, DEPs were associated with oxidative stress-related responses, as well as VEGF, and MAPK pathways in MCF-7 cells. Protein-protein interaction (PPI) network analysis further highlighted several enriched clusters potentially associated with apoptotic processes. The enriched clusters were supported by the human apoptosis-associated proteins arrays, which showed significant alterations in apoptosis-associated proteins levels. The 8 h exposure condition was associated with early apoptotic-related responses, whereas 24 h exposure condition appeared to represent a later phase of cellular response following prolonged exposure to Suma CTX. Collectively, exposure to Suma CTX resulted in differential proteomic alterations linked to multiple signalling pathways in a time- and concentration-dependent manner, along with remarkable changes in apoptosis-associated proteins.
Silva et al. (2026) studied this question.